The invention relates generally to osteotomy techniques and more particularly to an apparatus and method for performing cuneiform osteotomy.
Various techniques have been developed over the years for performing cuneiform osteotomy; that is, surgical removal of a bone wedge such as from a leg bone to correct impairments to the bone, the musculature or the ligamental support associated therewith.
The cranial or anterior cruciate ligament restrains cranial drawer or sliding motion of the tibia of a dog. When the cranial cruciate ligament is disrupted or injured, the tibia moves interiorly with respect to the femur, leading to further injury of the musculature, ligaments or meniscus. A wide variety of methods of repairing the cranial cruciate ligament have been suggested ranging from collagen ligament implants to synthetic ligament implants. Extra-articular repair devices have also been proposed, but none of these has been successful. Collagen implants stretch with use, leaving the knee area unstable, while synthetic implants are unable to withstand the varied forces exerted on the knee. Extra-articular repairs decrease mobility and place undue stress on the soft tissue surrounding the joint which is not designed for constant loads.
It has been recognized that one problem with most techniques for repairing a dog's cranial cruciate ligament is that the phenomenon of cranial tibial thrust has not been appreciated. This phenomenon results from the natural slope of the tibial plateau which results in force factors having compressive and cranial or anterior components. The compressive components are satisfactorily absorbed by the tibia, as are the cranial tibial forces when the cranial cruciate ligament is operating satisfactorily. When the cranial cruciate ligament is weakened by injury or is congenitally malformed, cranial tibial thrust can be a problem. Many prior efforts at repair of a weakened cranial cruciate ligament ignore the cranial tibial thrust phenomenon and have failed to recognize that this phenomenon results in the ligament being placed under stress while healing was intended to occur. Such stress clearly retards or prevents any such healing.
Once cranial cruciate rupture occurs, so-called cranial drawer or sliding motion, that is, unrestrained motion of the tibia following such rupture, results in more severe injury to the dog's leg. Surgical attempts have been addressed to restraining cranial draw motion but, until recently, no attempt has been made to deal with internally generated cranial tibial thrust.
The cranial tibial cuneiform osteotomy was developed to address the cranial tibial thrust phenomenon. It involves removing a wedge from the distal third of the tibia, and rejoining the bone using an osteopathic compression plate. This technique flattens the tibial plane and thereby eliminates cranial tibial thrust, permitting the cranial cruciate ligament to heal normally in a non-stressed condition.
While the cranial tibial cuneiform osteotomy has provided a solution to the afore-described problems, the operation itself has, until now, been somewhat cumbersome. It has required a substantial amount of skill in order to remove an appropriate wedge of bone which would flatten the tibial plane. The positioning of the drill holes by which the osteopathic compression plate has been mounted is also critical and has presented another technical problem with the operation. The operation has been further complicated by the fact that means has not been provided for supporting the osteopathic saw during the cutting of the bone. Even for the most skilled surgeon, this lack of support can and often does present difficulties. This is an operation which is performed regularly but typically not on a daily basis so that any device developed to faciliate the operation should be low in cost, relatively small due to storage space limitations, and should be easy to use by an veterinary surgeon who may not perform the operation on a regular basis.
It is an object of the present invention to provide an apparatus and method which meets the afore-described problems. More specifically, the invention has as its objects the following:
(1) to provide a surgical technique which eliminates cranial tibial thrust forces and thereby causes forces on the tibia to be compressive rather than angular, facilitating proper healing of the associated muscles and ligaments;
(2) to provide a device which fac:litates cranial tibial cuneiform osteotomy by a veterinary surgeon who does not have an opportunity to perform such operations on a regular basis;
(3) the provision of a device useable in cuneiform osteotomies which is simple in structure, inexpensive, physically small, and which will be long-lasting;
(4) to develop an apparatus for performing a cuneiform osteotomy which facilitates the precise positioning of osteopathic compression plate holes and which predetermines the exact amount and shape of bone to be removed; and
(5) to provide an apparatus and method for performing a cuneiform osteotomy in which the osteopathic saw is supported and precisely positioned without the use of intricate, expensive equipment, or a high degree of skill on the part of the surgeon.